Beyond that it's pulling from a finite pot. Every Hz you allocate to upstream is one less Hz you can allocate to downstream. Fiber doesn't have this constraint

Beyond that it's pulling from a finite pot. Every Hz you allocate to upstream is one less Hz you can allocate to downstream. Fiber doesn't have this constraint. It's trivial (and common) to deploy a pair to each premise, but, even if you don't want to do that you can shine light in both directions on the same piece of glass and reasonably* run a terabit across a single fiber (not a pair).